DEVELOPMENT OF SOIL SURVEY METHODS FOR URBAN AREAS

Urban soils are the foundation of urban ecosystems and play a vital role in long-term urban sustainability and resiliency. Accurate soil surveys of urban areas should be done at high resolution since extensive human activities often result in urban soils being highly disturbed, and spatially variable. Besides heterogeneity, one of the unique and challenging aspects of urban soil is its nature and properties of organic carbon with a significant percentage of black carbon (a particulate product of incomplete combustion), which is less biologically active. Thus, in order to determine the ability of a soil to support biological activity and supply nutrients for plant growth, the properties of organic carbon need to be assessed. Conventional USDA-Natural Resources Conservation Service (NRCS) methods take considerable time for full characterization of collected soil samples. This limitation could be overcome by geophysical tools such as, ground-penetrating radar (GPR) and electromagnetic induction (EMI), which can image large areas in a relatively short time without excavating the soils. These tools can map subsurface features and predetermine the degree of heterogeneity, which can provide useful information for representative site selection. How well these geophysical data correlate with site characteristics, however, has not yet been well established. In this project approximately 14 soil series covering a wide range of soil conditions will be investigated across New York City. From 4 sites, bulk density samples and bulk samples were already collected for laboratory determination of total C/N, black carbon, readily labile C and N, TOC, pH and soluble salts, plant available nutrients, microbial communities, and artifacts using standard protocols in the NRCS Field and Lab Analysis. In addition, GPR and EMI will be used to identify vertical differences in texture, consistence, artifact content, thickness of layers, and depth to the water table or restrictive horizons at each site. The results will be compared with conventional methods to evaluate the feasibility of these new methods to complement traditional approaches. Our findings and the soil survey methods developed will help soil practitioners and decision-makers in protecting, conserving, and managing urban soils for an ever-expanding world population.